### Abstract

The moment equation approach to neoclassical processes is used to derive the linearized electrostatic perturbed flows, currents, and resistive MHD-like equations for a tokamak plasma. The new features of the resultant "neoclassical magnetohydrodynamics," which requires a multiple length scale analysis for the parallel eigenfunction, but is valid in the experimentally relevant banana-plateau regime of collisionality, are: (1) a global Ohm's law that includes a fluctuating bootstrap current resulting from the "parallel" electron viscous damping (at rate μ_{e}) of the poloidal flow due to the perturbed radial pressure gradient; (2) reduction of the curvature effects to their flux surface average because Pfirsch-Schlüter currents cancel out the lowest-order geodesic curvature effects: (3) an increased polarization drift contribution with B^{-2}, replaced by B_{⊖}^{-2}, where B_{⊖} is the poloidal magnetic field component. An electrostatic eigenmode equation is determined from ▽·J̃=0. For the unstable fluid-like eigenmodes, the new viscous damping effects dominate (by ε^{-3/2}) over the curvature effects, but the growth rates still scale roughly like resistive-g or resistive-ballooning modes, γ_{μ}τ_{Α}∼ n^{2/3}S_{N}^{1/3}β_{T}^{2/3}(μ _{e}/ν_{e})^{1/3}. Diamagnetic drift frequency corrections to these new modes are also discussed.

Original language | English |
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Pages (from-to) | 1845-1858 |

Number of pages | 14 |

Journal | Physics of Fluids |

Volume | 28 |

Issue number | 6 |

DOIs | |

Publication status | Published - 1985 Jan 1 |

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### All Science Journal Classification (ASJC) codes

- Computational Mechanics
- Condensed Matter Physics
- Mechanics of Materials
- Mechanical Engineering
- Fluid Flow and Transfer Processes